3,342 research outputs found
Lone Wolf, Canis lupus, Displaced from a Kill by an Adult Black Bear, Ursus americanus, in Northeastern Alberta
Wolf (Canis lupus) packs are generally competitively dominant over Black Bears (Ursus americanus); however, less is known about lone Wolf-Black Bear interactions. We report an observation of a lone Wolf and an adult Black Bear at a kill made by the Wolf in northeastern Alberta. In this instance, the bear chased the Wolf from the kill site. Our observation supports the hypothesis that Wolf-Black Bear interactions may fit the pattern of asymmetrical interference competition when the interaction involves a lone Wolf rather than a pack
Evidence of Arboreal Lichen Use in Peatlands by White-tailed Deer, Odocoileus virginianus, in Northeastern Alberta
Within the past 10 to 15 years, White-tailed Deer (Odocoileus virginianus) have extended their geographical range to include most of northern Alberta. In the boreal forest they are most abundant in well-drained upland habitat. We report the occurrence of unusually large numbers of deer seen in a large fen complex in the west side of the Athabasca River Caribou range in northeastern Alberta. Further, we report an observation that suggests that deer may be using arboreal lichen (old man’s beard; Bryoria spp. and Usnea spp.) as a winter food in this region. We discuss the potential ecological ramifications of this observation for Woodland Caribou (Rangifer tarandus caribou) in northeastern Alberta
Wolf, Canis lupus, Pup Mortality: Interspecific Predation or Non-Parental Infanticide?
A breeding male Gray Wolf, Canis lupus, equipped with a GPS collar was documented going to the den site of another Gray Wolf pack. This trip was coincident with an attack on the den of the other pack and the occurrence of a dead and partially consumed Gray Wolf pup at the same location. We present two possible explanations - interspecific predation and non-parental infanticide - to account for this observation. Because the Gray Wolf with the GPS collar and his mate were first-time breeders and were attempting to establish a territory space of their own, we speculate that, based on the available evidence, this observation most likely represents a case of non-parental infanticide that fits the predictions of the resource competition hypothesis
The GPS craze: six questions to address before deciding to deploy GPS technology on wildlife
GPS and satellite technology for studies on wildlife have improved substantially over the past decade. It is now possible to collect fine-scale location data from migratory animals, animals that have previously been too small to deploy GPS devices on, and other difficult-to-study species. Often researchers and managers have formatted well-defined ecological or conservation questions prior to deploying GPS on animals, whereas other times it is arguably done simply because the technology is now available to do so. We review and discuss six important interrelated questions that should be addressed when planning a study requiring location data. Answers will clarify whether GPS technology is required and whether its use would increase efficiency of data collection and learning from location data. Specifically, what are required: (1) ecological question(s); (2) frequency and duration of data collection; (3) sample size; (4) hardware (VHF or GPS or satellite) and accessories; (5) environmental data; and (6) data-management and analysis procedures? This approach increases the chance that the appropriate technology will be deployed, budgets will be realistic, and data will be sufficient (but not excessive) to answer the ecological questions of interest. The expected results are important advances in ecological science and evidence-based management decisions
Transits and Occultations of an Earth-Sized Planet in an 8.5-Hour Orbit
We report the discovery of an Earth-sized planet () in
an 8.5-hour orbit around a late G-type star (KIC 8435766, Kepler-78). The
object was identified in a search for short-period planets in the {\it Kepler}
database and confirmed to be a transiting planet (as opposed to an eclipsing
stellar system) through the absence of ellipsoidal light variations or
substantial radial-velocity variations. The unusually short orbital period and
the relative brightness of the host star ( = 11.5) enable robust
detections of the changing illumination of the visible hemisphere of the
planet, as well as the occultations of the planet by the star. We interpret
these signals as representing a combination of reflected and reprocessed light,
with the highest planet dayside temperature in the range of 2300 K to 3100 K.
Follow-up spectroscopy combined with finer sampling photometric observations
will further pin down the system parameters and may even yield the mass of the
planet.Comment: Accepted for publication, ApJ, 10 pages and 6 figure
The Challenge of Wide-Field Transit Surveys: The Case of GSC 01944-02289
Wide-field searches for transiting extra-solar giant planets face the
difficult challenge of separating true transit events from the numerous false
positives caused by isolated or blended eclipsing binary systems. We describe
here the investigation of GSC 01944-02289, a very promising candidate for a
transiting brown dwarf detected by the Transatlantic Exoplanet Survey (TrES)
network. The photometry and radial velocity observations suggested that the
candidate was an object of substellar mass in orbit around an F star. However,
careful analysis of the spectral line shapes revealed a pattern of variations
consistent with the presence of another star whose motion produced the
asymmetries observed in the spectral lines of the brightest star. Detailed
simulations of blend models composed of an eclipsing binary plus a third star
diluting the eclipses were compared with the observed light curve and used to
derive the properties of the three components. Our photometric and
spectroscopic observations are fully consistent with a blend model of a
hierarchical triple system composed of an eclipsing binary with G0V and M3V
components in orbit around a slightly evolved F5 dwarf. We believe that this
investigation will be helpful to other groups pursuing wide-field transit
searches as this type of false detection could be more common than true
transiting planets, and difficult to identify.Comment: To appear in ApJ, v. 621, 2005 March 1
Discovery and Precise Characterization by the MEarth Project of LP 661-13, an Eclipsing Binary Consisting of Two Fully Convective Low-mass Stars
We report the detection of stellar eclipses in the LP 661-13 system. We
present the discovery and characterization of this system, including high
resolution spectroscopic radial velocities and a photometric solution spanning
two observing seasons. LP 661-13 is a low mass binary system with an orbital
period of days at a distance of parsecs. LP 661-13A is a star while LP
661-13B is a star. The radius of each component
is and ,
respectively. We detect out of eclipse modulations at a period slightly shorter
than the orbital period, implying that at least one of the components is not
rotating synchronously. We find that each component is slightly inflated
compared to stellar models, and that this cannot be reconciled through age or
metallicity effects. As a nearby eclipsing binary system where both components
are near or below the full-convection limit, LP 661-13 will be a valuable test
of models for the structure of cool dwarf stars.Comment: 24 pages, 8 tables, 6 figures. Submitted to ApJ, comments welcom
Line Broadening in Field Metal-poor Red Giant and Red Horizontal Branch Stars
We report 349 radial velocities for 45 metal-poor field red giant and red
horizontal branch stars. We have have identified one new spectroscopic binary,
HD 4306, and one possible such system, HD 184711. We also report 57 radial
velocities for 11 of the 91 stars reported on previously by Carney et al.
(2003). As was found in the previous study, radial velocity "jitter" is present
in many of the most luminous stars. Excluding stars showing spectroscopic
binary orbital motion, all 7 of the red giants with M(V) <= -2.0 display
jitter, as well as 3 of the 14 stars with -2.0 <= M(V) <= -1.4. We have also
measured line broadening in all of the new spectra, using synthetic spectra as
templates. The most luminous red giants show significant line broadening, as do
many of the red horizontal branch stars, and we discuss briefly possible
causes.Comment: To appear in the Astronomical Journa
Jupiter Analogues Orbit Stars with an Average Metallicity Close to that of the Sun
Jupiter played an important role in determining the structure and
configuration of the Solar System. Whereas hot-Jupiter type exoplanets
preferentially form around metal-rich stars, the conditions required for the
formation of planets with masses, orbits and eccentricities comparable to
Jupiter (Jupiter analogues) are unknown. Using spectroscopic metallicities, we
show that stars hosting Jupiter analogues have an average metallicity close to
solar, in contrast to their hot-Jupiter and eccentric cool Jupiter
counterparts, which orbit stars with super-solar metallicities. Furthermore,
the eccentricities of Jupiter analogues increase with host star metallicity,
suggesting that planet-planet scatterings producing highly eccentric cool
Jupiters could be more common in metal-rich environments. To investigate a
possible explanation for these metallicity trends, we compare the observations
to numerical simulations, which indicate that metal-rich stars typically form
multiple Jupiters, leading to planet-planet interactions and, hence, a
prevalence of either eccentric cool Jupiters or hot-Jupiters with circularized
orbits. Although the samples are small and exhibit variations in their
metallicities, suggesting that numerous processes other than metallicity affect
the formation of planetary systems, the data in hand suggests that Jupiter
analogues and terrestrial-sized planets form around stars with average
metallicities close to solar, whereas high metallicity systems preferentially
host eccentric cool Jupiter or hot-Jupiters, indicating higher metallicity
systems may not be favorable for the formation of planetary systems akin to the
Solar System.Comment: Accepted in Ap
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